<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <span id="spanId">Hello Span</span> <br/>
    <button onclick="clickMe()">点击</button>

    <script>
        function clickMe() {
            var spanObj =  document.getElementById('spanId');
            //spanObj.innerText = '<h1 style="color: red">innerText</h1>';
            spanObj.innerHTML = '<h1 style="color: red">innerText</h1>';
        }
    </script>
</body>
</html>